This invention relates to devices for cleaning out mud tanks of hydrovac units.
In hydrovac operations, water is used to blast a hole or trench in soil and the fluidized soil thus created is sucked into a mud tank. The water in the mud tank is filtered and recirculated for use in blasting the hole, while mud accumulates in the mud tank. Periodically, the mud has to be removed from the mud tank. In the past, removal of the mud has been done with hoists, in which the tank is lifted and the mud dumped. This is not efficient, and the resulting vehicle is fairly complex.
In U.S. patent application Ser. No. 09/656,624, filed Sep. 7, 2000, and Canadian patent application No. 2,317,667, published Mar. 6, 2001, the inventor has proposed a solution to the inefficient removal of mud from a mud tank. In those applications, there is provided, in accordance with an embodiment of the invention, a mud tank cleaning system, comprising a mud tank having confining walls; an opening in the confining walls of the mud tank; a removable cover mounted on the mud tank over the opening; a sweep mounted in the mud tank and being operable to sweep mud in the mud tank towards the opening in the confining walls; and a sweep drive mechanism operably connected to the sweep for operating the sweep. The mud collects in a trough at the base of the confining walls, from where it is swept by the sweep through the opening.
This prior device relies upon gravity to pull debris into the trough. The inventor has now proposed a cleaning mechanism to improve the collection of the debris in the trough and thus facilitate rapid and complete cleaning of the mud tank.
There is therefore provided, in accordance with an aspect of the invention, a mud tank cleaning system that includes a debris collection sweep that drives debris towards a collection zone in a mud tank, from whence the debris can easily be mechanically disposed of through an opening in the mud tank. Preferably, the collection zone is in a central depressed part of the mud tank to allow gravity to assist in moving debris towards the collection zone. Preferably, a pair of collection sweeps are used on opposed sides of the collection zone. The collection sweeps are preferably pivotally mounted to follow an arcuate path along the surface of a cylindrical confining wall of the mud tank. Sweep drive mechanisms operate the sweeps. The collection sweeps are preferably used in conjunction with a disposal sweep that sweeps debris collected in the collection zone by the collection sweeps out of the collection zone and through the opening in the mud tank, from where it may be readily disposed of. The mud tank is typically operated in conjunction with a hydrovac vehicle.
These and other aspects of the invention are described in the detailed description of the invention and claimed in the claims that follow.